Strobe not synching

Just took the camera out of the housing and shot it past the bare strobe sensor into the mirror. It syncs!

So does that likely just mean it's a cable issue (i.e. the cable isn't transmitting enough light)? If so, great, I'll look at trying a new cable.

Give it a try without the sync cables attached to the strobes...ie take your camera out of the housing and expose the sensor that the FO cable fixes to...take a pic pointing your camera flash to the strobe sensors. Run your test again.

If you get the same results then you'll know for sure that it is not a cable issue or vice versa....

Yes indeed the optical sensors are different sizes but at least on my strobes the FO cables with the large connector work on both types of strobes.
Based on all the data so far I strongly suspect the cable.
Bill

Just took the camera out of the housing and shot it past the bare strobe sensor into the mirror. It syncs!

So does that likely just mean it's a cable issue (i.e. the cable isn't transmitting enough light)? If so, great, I'll look at trying a new cable.

A lot of times there's a small break near the connector end. If you have a removable connector, you can just cut off the bad end and replace the connector. You just need to be able to see the light shine through if you hold one end up to a strong light.

If it seems to be ok, try cleanning off the inside of the housing optical window or seeing if anything is blocking the light from shining through. We just had a customer have awful problems, until we cleaned off the inside of the little connector window with some alcohol. Problem solved!

I have used Toslink connectors with Inon strobes for a while. If you make them short enough and polish the ends carefully they can work fine with sTTL but if you don't they can be very finicky. Inon FO cables seem to transmit at least 2x as much light as the Toslink ones at least by eye (yes I know that your eye is a logarithmic detector) but I am too lazy to test them properly.

In any case, I suspect that a "better" FO cable will solve the mystery.
Bill

I'm going to try getting my hands on another fiber optic cable to see if that helps.

I did try snipping the end of the current Toslink cable, but no better luck (light is definitely shining through, though). I'll polish up the sensor with some alcohol as well. Going to have to wait till tomorrow, though. Sick of shooting into the mirror.

...........I'll polish up the sensor with some alcohol as well. Going to have to wait till tomorrow, though. Sick of shooting into the mirror.

It's the insertion point on the camera housing that may need attention rather than the sensor on the strobe; would try flushing it first withwarm water using a syringe. The strobe sensor is plastic could alcohol affect that adversely?

So when you flipped the fiber optic cable around, did that cause the strobe in question to suddenly work? It should, or else the strobe itself is not calibrated the same way as the other, thus its threshold of firing is higher than the good strobe. Even so, the strobe in question firing itself at least 1/10 sec after it should cannot be due it not capturing only part of the light coming out of the toslink cable, since by 1/10 sec later, the duration of the flash has long been over.

Busy couple of days and we're leaving town through the weekend, but I'll get back to this when we return. Thanks, everyone for all the suggestions. Really hoping this can be fixed with a new cable and isn't something more serious.

Last night, at EMUP (our photo club), we dived in the delights of Stoney Cove, well-known to Brits who have to dive somewhere, when the weather is bad. One member's Inon D2000 was particularly balky. Back on dry land it turned out to be the housing end of the fibre-optic link that wasn't always picking up the camera's flash, depending on how much tension was put on the fibre-optic cable.

Using Inon and Nauticam cables I have never (touch wood!) had a problem.